The present invention relates to an interfacing technology, which is mainly employed in personal computers and can enlarge a number of and a kind of devices connectable to the personal computers.
A personal computer, put in the market, incorporates connectors (also referred to as terminals or connecting ports) to which various kinds of peripheral devices can be coupled. Such the personal computer also incorporates expansion slots (such as PCI, ISA, VL, etc.), mounted on a circuit board disposed in the interior of the personal computer, to expand its functions. In order to increase new functions in addition to default functions of the personal computer, various kinds of circuit boards can be mounted onto such the expansion slots. This makes it possible to add various kinds of new functions to the personal computer. For instance, one of the new functions is an interfacing function for coupling an external peripheral device to the personal computer, and circuit boards having such the interfacing function include multi I/O boards, SCSI (Small Computer System Interface) boards, USB (Universal Serial Bus) boards, IEEE1394 boards, etc.
Even if such a board as mentioned above can be added to the personal computer, however, a number of connecting ports for the interfacing function is limited.
Further, when a SCSI or a USB interface is employed, a predetermined number of peripheral devices can be coupled to the personal computer in a daisy-chain mode. Recently, the USB interface has been proliferated widely, since the USB interface has not only a high-adaptability for general purposes, but also high-speed and intelligent features, compared to the SCSI interface.
In fact, external data-storing devices, which employ the USB and/or IEEE1394 interface(s) for coupling it to the personal computer, such as a MOD (Magnet-Optics Disk Drive), a HDD (Hard Disk Drive), a CD-R/RW (Recordable/ReWritable Compact Disk Drive), etc., have been widely put in the market.
FIG. 7 shows a personal computer and an external data-storing device, which are coupled each other. In FIG. 7, numeral 1 indicates a personal computer, to which an external data-storing device is coupled through a USB cable.
In most of such the external data-storing devices, a bridge system having a conventional ATAPI or a conventional SCSI, serving as an interface, is added to an external data-storing unit (such as an inhouse-MOD, an inhouse-HDD, an inhouse-CD-R/RW, etc., so to speak).
This is because of the following reasons.    1. An enormous amount of cost and time would be required for developing and manufacturing external data-storing units having a new interface facility.    2. It is impossible to determine at present what kind of interface facility should be the mainstream for the future.
Owing to the abovementioned reasons, the meritorious solution has been to develop or purchase the bridge system for converting the ATAPI or the SCSI into the USB or the IEEE1394 interface, in order to externally connect it to the personal computer.
FIG. 8 shows an example of an outsight configuration of an external data-storing device having the USB or the IEEE1394 interface. This configuration makes conventional external data-storing unit 10 usable by adding bridge system 20 to conventional external data-storing unit 10. Bridge system 20 is assembled by mounting various kinds of necessary parts onto the circuit board. In bridge system 20, numerals 21, 22, 23 and 24 indicate a power jack, a power switch, a USB or an IEEE1394 connector and an ATAPI or a SCSI connector, respectively, and those are connected onto bridge system 20. As described in the above, the bridge system allows the data-storing unit having a conventional ATAPI or a conventional SCSI to be utilized as the data-storing device being active with the USB or the IEEE1394 interface.
One or at most two of USB connecting ports has/have been equipped in a conventional personal computer put in the market, and as for IEEE1394 connecting ports, only one port has been allocated for its purpose in the personal computer. Therefore, when a certain small number of devices occupy those USB or IEEE1394 connecting ports, other devices could not be connected to the personal computer. To overcome this inconvenience, a unit named “Hub” has been provided as a “data-distributing” unit, which makes a “multiple-distribution wiring” possible.
It has been a problem, however, that employing such the “Hub” makes wirings between peripheral devices complicated. Further, although the USB or the IEEE1394 interface has such a feature that a power current can be also supplied to the peripheral device through the interface, the “Hub” is not always provided with a function of distributing the power current to plural devices. As a result, there have been many cases that some of the peripheral devices connected through the “Hub” cannot work properly.